The present invention is directed to medical and laboratory biological specimen collecting and testing apparatus. Diagnostic cytology is the area of clinical pathology in which diagnoses are made based on microscopic examination of cell and other biological samples taken from many body sites. The accuracy of the diagnosis depends on both adequate patient sampling and culture and slide preparation procedures that result in optimally interpretable specimens.
In peritoneal dialysis patients, it is important not only to culture the fluid from the chronic ambulatory patients, but also to determine whether or not there are inflammatory cells present in that fluid. Patients who have frank peritonitis with rebound tenderness, guarding, fever and leukocytosis are not difficult to diagnose. Nephrologists seek early diagnoses of those patients who have some symptomology, but have mild tenderness, low grade fever and no abdominal rigidity.
Nephrologists will frequently culture the dialysate in one of many ways, demonstrating the fact that there is no perfect method to detect early peritonitis. Most nephrologists will also extract some fluid from the abdominal cavity and do a cell count on a hemocytometer. The latter is to support the results of the culture, which in and of itself may not distinguish between true peritonitis and a simple colonization of bacteria.
The organisms which are most common in peritonitis are the enterobacteriacae, particularly E. coli and the coagulase negative staphylcoccus. The latter is particularly a problem since it is a commensal organism frequently found as a contaminant. Therefore, when one examines a minimum of fifty mililiters of fluid and finds white cells and bacteria, the evidence becomes stronger that an early inflammatory disease is present and therapy can be started with a much better clinical outcome and at much less cost.
Under normal conditions, urine contains a small number of cells and other particulate matter shed from the entire length of the urinary tract. These materials are usually known as urinary sediments. Typical urinary sediments consist of red blood cells, white blood cells, epithelial cells, casts, mucus and crystals. In addition, sporatic urinary sediment such as bacteria, yeast, parasites and spermatozoa occur in patients suffering from various types of disorders or engaging in particular activities. With disease, these cells as well as other formed elements are often increased and may help to localize the site and type of injury. For example, excessive numbers of red blood cells may indicate tumor, stones or imflammation. Excessive number of leukocytes may indicate infection or other inflammatory disease. In contrast to the hypocellular nature of normal urine, neoplastic cells (e.g., transitional, squamous and columnar cells) are shed more frequently in malignant conditions of the bladder epithelium.
Until recently the technique of preparing the best possible specimen has not drawn as much attention as it deserves. Preparative shortcomings such as uneven cell distribution and variable staining results that result in suboptimal slides can marginally be tolerated because the human observer can still evaluate these slides and correct for inconsistencies. Recently, however, interest in a better quality slide has increased. The increased use of fine-needle aspirates for diagnostic purposes, greater use of image cytometry and a greater concern about cytology quality control issues are a few of the reasons behind the movement to improve preparation techniques. Additional tests performed with new technologies such as immunocytochemistry and image analysis are being evaluated. These tests require high quality specimens to fully achieve their capabilities. Clearly, preparation and fixation protocols that are the same and reproducible for each sample type are needed.
Membrane filter techniques are an improvement because they are performed in the cytology laboratory where they can be better controlled. An advantage of using a cell suspension is that the sample can be dispersed to minimize large clumps and provide a more even cell distribution in the resulting slide. Typically, the cell suspension is dispersed by vortexing or with a syringe.
In the membrane filtration technique the cell suspension is both concentrated and collected on a membrane filter made of cellulose or polycarbonate. This technique is used in many cases when the cell concentration is low, as in cerebrospinal fluid. Cells in body fluid or in a preservation fluid are put in a funnel, collected, rinsed and prefixed on the filter and the filter with the prefixed cells is then put on a slide. Because the filter background interferes with the inspection of the cells, procedures have been developed to dissolve the filter. However, because the procedure for dissolving the filter also affects the morphology of the cells, this technique does carry some risks.
Although urine and dialysis fluid are the specimens discussed for diagnosis, other fluids such as seminal, synovial, pleural, pericardial, peritoneal, amniotic and sweat fluids are associated with specific conditions and diseases. It is important during the collection handling of biological fluid specimens that the potential of specimen deterioration, contamination and the spread of any infection from the specimen be minimized.
A typical specimen collecting apparatus is shown by U.S. Pat. No. 4,741,S46. This apparatus includes a base stand which supports the specimen vial in an upright position. A funnel is inserted in the open end of the specimen vial and surrounds and encloses the upper portion of the vial. The base stand has an upwardly extending tubular wall which at least partially surrounds the vial in connection with the cap and allows the user to remove the vial without touching the surface or coming in contact with the specimen. Examples of various types of liquid containers for collecting and transporting urine are shown by U.S. Pat. Nos. 3,777,739; 3,881,465; 4,042,337; 4,084,937; 4,244,920; 4,492,258 and 4,700,714.
Another specimen collection device shown by U.S. Pat. No. 4,040,791 discloses a collection receptacle having a nipple upon which is mounted a specimen container which receives a predetermined amount of the specimen in a sealed condition. The specimen container is provided with an integrally formed cap which is placed over the opening in which the collector nipple is inserted. U.S. Pat. No. 4,557,274 discloses a midstream urine collector having a funnel which transmits urine into a cup member which is covered by a membrane cover.
A combined strip testing device and collection apparatus is shown by U.S. Pat. No. 4,473,530 and is directed to an apparatus which integrates testing and collection by having chemical reagent test strips present within the tube together with specific gravity reading means allowing immediate testing of the urine. U.S. Pat. No. 4,573,983 is directed towards a liquid collection system having an antiseptic member on the discharge section which uses a filter of air and bacteria impervious material to filter the urine.
A number of investigators involved in automated measurement of cervical smears have developed instruments that incorporated cell collection techniques. One group developed an instrument that includes a rotor device to disperse cells aggregated by mucus or other non-cellular bonds. Use of the rotor results in a high degree of cell dispersion and a reduction of cell clumps while maintaining diagnostic abnormal cell clusters. Then the desired number of cells are collected on a polycarbonate filter membrane and deposited on a slide by simultaneous pressure and fixation. The filtration removes much of the non-diagnostic background debris and most red blood cells resulting in a cleaner slide without losing important diagnostic clues.
Cytic Corp. has enhanced and refined this earlier instrumentation in designing the ThinPrep Processor. Gentle dispersion breaks up large clumps while keeping diagnostic clusters intact. Most red blood cells and insignificant debris are removed. The cellular material is then transferred to the slide with controlled density. This process is non-aerosoling, non-contaminating, low cost and fully automated.
It is therefore desirable to provide an easy to handle disposable apparatus and a method which transports a fluid sample through staged filters to capture a concentrated amount of cell particulate matter and bacteria from the fluid for testing.